1. Field of the Invention
This invention relates generally to internal combustion engines equipped with electronic fuel injection systems and exhaust treatment devices. More particularly this invention relates to means associated with engines of the type described for detecting engine malfunctions that could cause excessive temperatures which might damage or destroy the exhaust treatment device.
2. Description of the Prior Art
Complete control of exhaust emissions from internal combustion engines, with the possible exception of gas turbines, appears to require treatment of the exhaust products with catalytic converters and/or manifold thermal reactors. Both of these exhaust treatment devices depend upon achieving and maintaining relatively high temperatures to complete the oxidation and/or reduction of the exhaust emission products. The devices are designed to operate safely at temperatures based upon normal engine operation. However, it is known that a misfiring engine can result in substantial temperature increases within the exhaust treatment device to the point that the exhaust treatment structure can be oxidized or otherwise damaged or destroyed. This occurs because each engine misfire allows the unburned fuel/air charge in the particular cylinder subject to the misfire to be discharged into the highly reactive environment of the exhaust treatment device, whereby the energy normally released in the cylinder to produce power is converted into heat that results in temperatures beyond the design limits of the exhaust treatment device. Prior to the present invention there has not been apparatus for detecting such misfiring and for inhibiting operation of the engine in response thereto.